Douglas Isbell
Headquarters, Washington, DC March 19, 1998
(Phone: 202/358-1753)
RELEASE: 98-47
TWO STUDIES WILL REFINE AND EXPAND SOLAR MONITORING TASK
The Naval Research Laboratory, Washington, DC, and the
University of Colorado's Laboratory for Atmospheric and Space
Physics in Boulder have been selected by NASA's Office of Earth
Science to conduct parallel six-month definition studies of a
new small satellite to monitor variations in the amount of
radiant solar energy that reaches Earth.
The precise measurements to be obtained by the Total Solar
Irradiance Mission (TSIM) will help scientists better
understand the relationship between the Sun's variable energy
output and its effects on Earth's climate. The six-month
feasibility studies will focus on the development of a
preliminary system design and operations concept for the cost-
capped $23 million mission.
NASA has been measuring the total radiative output of the
Sun from the unique perspective of space since the late 1970s.
The current sensor being used is called the Active Cavity
Radiometer Irradiance Monitor (ACRIM). NASA has flown two
ACRIM instruments, including the ACRIM-II instrument onboard
NASA's Upper Atmosphere Research Satellite. A third ACRIM
instrument is scheduled for launch aboard a dedicated small
satellite in October 1999.
TSIM will extend the broad data set gathered by the ACRIM
series while exploring a new capability to measure solar
irradiance in two discreet spectral bands. Once proven, this
operationally oriented capability is a candidate for flight
aboard future National Polar Orbiting Environmental Satellite
System missions being planned by a tri-agency partnership among
NASA, the Department of Defense and the National Oceanic and
Atmospheric Administration.
"TSIM will be developed in 36 months or less using the same
key principles of 'faster, better, cheaper' spacecraft
demonstrated by the agency's Discovery Program," said Dr.
Ghassem Asrar, NASA Associate Administrator for Earth Science.
"We hope to obtain an instrument payload that is lighter and
more technologically advanced, yet provides an exciting
additional capability that will give us new knowledge about our
climate and why it varies."
TSIM is part of NASA's Earth Observing System, a series of
advanced remote-sensing satellites designed to provide
simultaneous measurements of a broad range of physical,
chemical and biological processes to enable researchers to
study the Earth's land, oceans, air, ice and life as a total
system. TSIM also will serve as NASA’s contribution to the
joint small Science Satellite (SciSat) program with the
Canadian Space Agency. NASA and Canada have committed to
developing independent science research missions to be launched
on a NASA-funded launch vehicle in December 2001, with shared
data after launch.
The two selected teams will document their analyses for
NASA review by the end of 1998, with one team being selected
to proceed with development. TSIM program management will be
provided by NASA's Goddard Space Flight Center in Greenbelt,
MD.
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